Brenner was a male Human Starfleet crewmember in the 23rd century. He served in the command division aboard the USS Enterprise in 2266 under the command of Captain James T. Kirk, during the historic five-year mission. He was assigned to the forward phaser control room as a phaser specialist.
That same year, when the Enterprise went to condition red upon news of a Romulan Bird-of-Prey attacking Outpost 4, all crewmembers reported to battle stations. Brenner and Fields reported on the readiness of the weapon batteries. He was injured by radiation burns, when the Enterprise destroyed an atomic weapon. He reported to the sickbay for treatment. (TOS: "Balance of Terror")